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Plans for a bullet trap-with pictures***Looking for opinions***

I've had an idea for a bullet trap rolling around in my head for a while. Figured if I'm going through all this trouble of scrounging lead to make boolits, why waste it all by shooting it into the ground. With a bullet trap I'll be able to recover and re use all my own lead that I practice with at home.

Last night I figured I'd give google sketchup a shot and see if I could get it to work. Not only did it work, it did the hard part of figuring out measurements and angles so I didn't have to. Made everything to scale too. Some of the measurements aren't exact, but pretty darn close. The bullets would enter through the slot in the rear and spin around in the spin chamber until they lose enough energy to fall out the hole in the bottom. I figured I could just put a 5 gallon bucket under the hole to catch the bullets as they drop out. The steep angle of the funnel on the bottom should push any back up that make it to the bottom and still have some energy left in them.

So I've included these pictures to get some opinions from all of you. Let me hear your thoughts on the results. Does it look like it would work? Seems to me that it would be feasible and I have a buddy that would build it for me. Figured the whole thing would be built on a small utility trailer frame to make it movable.

Front view

Side view

Top view

A couple 3D views. There are a few spots that didn't fill in on the spin chamber that you can see but other than that it turned out ok. Also I deleted the top so you could see inside it.

I built this one for a commercial gunsmith a couple of decades ago. I tested it with full auto fire from both the M16 & M60, as well as things like the .22-284 & pistols. Even tried a BB gun.

The 'smiths shoot 300 mags & shotguns into it all the time. Never had anything "bounce back" from it. Kind of fun to watch them dump a couple of 3.5" 12ga mags into it. The plates are .375 thick AR400 steel.

Your design looks good for handgun stuff, but may be easier to fabricate as plates.

everything I have read says that the outside slope should come in on the tangent to the circle, pretty close to what you have. It can take a while for the spin down to occur in the cylinder. I also read somewhere that it is better to have the cylinder horizontal to the ground versus the vertical position.

There is an excellent diagram for a bullet trap in the book "Sharpshooting for sport and war" by Wolfe publications.

Thing was designed for full sized center fire rifle rounds.

Thanks for the tip, checking it out now.

Originally Posted by manleyjt

everything I have read says that the outside slope should come in on the tangent to the circle, pretty close to what you have. It can take a while for the spin down to occur in the cylinder. I also read somewhere that it is better to have the cylinder horizontal to the ground versus the vertical position.

You will be able to tell us if it works though.

Yeah I got it as close as I could with the program. It's not perfect, more of a design concept drawing.

I'm thinking now that a horizontal cylinder might be a more simple design and be easier to build. Going to have to play around with it some more and see what I can come up with.

I do appreciate all the feedback. It helps me take a good thorough look at things before I jump in.

No need for a door really. The design I posted is self-cleaning. The scrap falls out the gap in the bottom.

I put the 'scope into that trap several times while testing it. Lead pistol bullets do not make a full revolution. Some jacketed rifle bullets don't hit the 4th plate.

There is no way for a bullet to get to the first plate without sliding down one of the 10 degree plates. This tends to spoil the stability, and helps to break up the jacketed bullets. 7.67x39 steel cores hit the first plate sideways.

That Greener trap in the old sharpshooter book tends to sling shards everywhere. Best to stay back 75 yards or so... It was really intended to localize a bullet at the butts.

do the sides on yours slop also? I like the idea of using plates to form the snail. I have all the stuff to make one like yours, but some additonal info would be appreciated.
Do you have a picture of it in competed form?

Looks to be 4 or 5 feet long x 1 to 1.5 feet tall x 1 ft or so wide? What did it weigh?

Any reason for the split botton entry slope (long plate and then short plate under it)?

The sides are parallel, but the opening is only 6x6. Since this is a test tank, the gunsmiths shoot with the muzzle in the opening - even a bad shot can only hit the sides @ 10 degrees or so.

Weight - It is heavy, since the final wrap at the outside edges of the side plates was 1/2" CRS.

The three piece throat is not as easy to understand from the pics. The two long plates provide the initial de-stabilization of the bullet. The throat between them is 1". That would leave the bullets a small window to pass through without skidding first. The secondary plate prohibits that. Nothing gets to the first plate in the snail without skidding first. Sorry I never took a good pic from the right perspective.

Different sized plates. Actually quite a bit of FEA went into that before it was built. The edges of the AR400 plate are slightly softer from cutting. The first snail plate is placed to keep those edges from seeing a strike, as well as at the proper angle to take a worst case hit. The next three plates are also arranged to protect the "soft" edges, and are a true snail.

The gap at the bottom makes it "self cleaning", and the next two plates size & angle act to destabilize things again. This thing shreds bullets. Steel cores from 8x57 czech stuff comes out in pieces. The design was "reduce the mass, reduce the energy".

The big gap under the first throat is for airflow. Since this thing is inside the shop, we wanted no health issues. On the front of the trap below the shooting area is a coupling for a HEPA vac. With the vac running you can't even smell the muzzle gasses from a 300 RUM. It all goes down the trap throat. A check of the vac shows plastic wad shards from shotguns. It is really clean.

The kid that did the FEA was an intern we had for the summer. Everything he said would happen did - I was actually amazed. I did not take a bunch of pics at the time, so I have no finished & installed pics. Pre-digital age, those are negative scans from film.

Question1) How noisy is this think in the shop?Does it give off a noticeable metallic ring when used? I was around a trap on this line and the shot was muffled but the ring of the hit was something else even with hearing protection.

Question 2) What filler metal did you use for the welds? We had some interesting results of weld breakage on a target backer used for larger hand gun loads, but it took some time and lots of shots. And I think our angle on the first deflection plate was too steep.

thanks for the additional info.

I wondered about the softening of the plate due to cutting. My uncle works part time at a shop that has a water jet and a flame cutter, I had really wanted to see the difference between pieces cut with them but have not had a chance with the ar series of steel.

We had some flame cut patters of knockdown targets that you could see the softening of the plate at the cut edges based on bullet strike when in use.

Very interesting about he construction details and the design work that went into it. Nice work

I also got to have fun poking holes in a piece of ar400. the plate was set on a plate base so target was perpendicular to the shot. A 223 and 270 poked holes like a paper punch, the 30-06 and 300 win mag made big dents then very large holes when the stressed area finally gave way. Angling the plat only 5 to 10 degrees forward stopped the hole poking. That day was very interesting and I learned a lot.

It was loud before it was wrapped. Adding the .500 thick CRS around the perimiter helped a lot. We discussed filling the dead spaces with ground landsscape rubber, but never did. The shop glued rubber backed commercial carpet to the flat sides, they said it cut things in half. It was never that loud to me.

The welds are ER70S6 wire, with 100% Co2 shield gas. The tacks were done at room temp, then the assembly was warmed to 200f before finish welding. Cooled under a (gasp!) asbestos blanket.

The plate was CNC flame cut by a local vendor. He was using an Oxy-Gasoline rig, which he claimed reduced the Heat Affected Zone. The HAZ was fairly narrow according to hardness tests we did.

You either had some very thin AR plate, or it was not AR400. A 3/8" piece of AR400 shrugs off M855 5.56 Nato ammo with a smile @ 0 degrees & 60 yards. Fixture fired @ 1 foot from the muzzle & 0 degrees it takes 5 rounds of M855 in the exact same spot to open a hole - yeah, I got paid to do that test. In full auto 5 would always open a hole & #6 would go through. In semi, with 10 seconds between shots it takes 9 - # 10 goes through.

The oxy-gasoline process is not common in the US, but it does cut better. The claims of 3x cutting speeds on 4.5 inch thick stock are well documented. It will also do things like cut a 6 inch thick stack of 1/4" diamond plate - all at once.

There is less sprayed metal out the back side, it all appears to be completely oxidized in the cut. Those are the as-cut edges in the picture.

Our vendor said part of the "magic" with machine cutting using gasoline was the higher fuel pressures. You can run liquid gasoline @ 100 psi safely in the torch tip, which means the O2 pressure in the heating flame can be higher too. More BTU's in the same space. And gasoline burns HOT.

your trap design is good, but necks too tightly at the end of the funnel. looks like you have a pipe about 12" diameter. unnecessarily large. i built something very similar out of 12 gauge sheet metal and it catches 22RF and sub sonic pistol bullets with a "pipe" of about 4" diameter and a wider funnel neck. if you are thinking 3000 FPS rifle ammo then you need AR 400 plate and it is easier to make out of overlapping flats, as it is very difficult to bend, but needs a specific welding technique. if 2000 fps castings are all you are throwing into it, 3/8 mild steel and a standard wall 4" ID pipe is enough to last a long time, much cheaper than AR 400, and easier to weld.

AR 400 of 1/4"+ thickness cannot be penetrated by less than 4000 fps. as for HAZ effect on AR 400. this is limited to what will be your weld zone, anyway. HAZ is about 1/3 the material thickness in oxy-fuel or air plasma in thicknesses up to 1/2", and less so in heavier stock, non-existent in water jet.

i'm a certified welding inspector, a fabrication and materials engineer, and have shot a lot of steel.

justashooter, I'm a hobby welder and want to make a trap for rimfire and 200 gr lswc out of a 1911 going about 700 fps. Trap would be outdoors at 25 yard line. Can you provide a photo and some more info on the trap you built? Thanks, Larry

thanks foryour comments. I would like to relay that I agree with what you said about the ar plate. The one thing I will say is that just because it is sold as one thing does not mean it really is. That is why it was sent back to the supplier with holes and dents. you pay the extra for what you need, not for the fun of it.

And HAZ does play into this topic. As if one does not account for it when running the bead to put steel targets together, you can shoot welds appart. A good welder should be able to do the job right, but not always is time/expertise allowed for when you are just making something that going to be shot at anyway.